CVE-2025-38250
📋 TL;DR
A use-after-free vulnerability in the Linux kernel's Bluetooth subsystem allows an attacker to cause memory corruption when multiple threads access a virtual HCI device simultaneously. This affects systems using Bluetooth functionality, particularly those with virtual HCI devices. The vulnerability can lead to system crashes or potential privilege escalation.
💻 Affected Systems
- Linux kernel
📦 What is this software?
Linux Kernel by Linux
The Linux Kernel is the core component of the Linux operating system, serving as the critical interface between computer hardware and software processes. As the heart of millions of servers, cloud infrastructure, embedded systems, Android devices, and IoT deployments worldwide, the Linux Kernel mana...
Learn more about Linux Kernel →Linux Kernel by Linux
The Linux Kernel is the core component of the Linux operating system, serving as the critical interface between computer hardware and software processes. As the heart of millions of servers, cloud infrastructure, embedded systems, Android devices, and IoT deployments worldwide, the Linux Kernel mana...
Learn more about Linux Kernel →Linux Kernel by Linux
The Linux Kernel is the core component of the Linux operating system, serving as the critical interface between computer hardware and software processes. As the heart of millions of servers, cloud infrastructure, embedded systems, Android devices, and IoT deployments worldwide, the Linux Kernel mana...
Learn more about Linux Kernel →Linux Kernel by Linux
The Linux Kernel is the core component of the Linux operating system, serving as the critical interface between computer hardware and software processes. As the heart of millions of servers, cloud infrastructure, embedded systems, Android devices, and IoT deployments worldwide, the Linux Kernel mana...
Learn more about Linux Kernel →Linux Kernel by Linux
The Linux Kernel is the core component of the Linux operating system, serving as the critical interface between computer hardware and software processes. As the heart of millions of servers, cloud infrastructure, embedded systems, Android devices, and IoT deployments worldwide, the Linux Kernel mana...
Learn more about Linux Kernel →Linux Kernel by Linux
The Linux Kernel is the core component of the Linux operating system, serving as the critical interface between computer hardware and software processes. As the heart of millions of servers, cloud infrastructure, embedded systems, Android devices, and IoT deployments worldwide, the Linux Kernel mana...
Learn more about Linux Kernel →⚠️ Risk & Real-World Impact
Worst Case
Kernel panic leading to denial of service, or potential privilege escalation to kernel-level code execution.
Likely Case
System crash or instability when Bluetooth operations are performed concurrently on virtual HCI devices.
If Mitigated
No impact if Bluetooth functionality is disabled or virtual HCI devices are not in use.
🎯 Exploit Status
Requires local access and ability to create multiple threads accessing Bluetooth devices concurrently. The syzbot report shows the race condition can be triggered.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: Fixed in kernel commits: 0e5c144c557df910ab64d9c25d06399a9a735e65, 1d6123102e9fbedc8d25bf4731da6d513173e49e, bc0819a25e04cd68ef3568cfa51b63118fea39a7, ce23b73f0f27e2dbeb81734a79db710f05aa33c6
Vendor Advisory: https://git.kernel.org/stable/c/0e5c144c557df910ab64d9c25d06399a9a735e65
Restart Required: Yes
Instructions:
1. Update Linux kernel to version containing the fix commits. 2. Check your distribution's security advisories for backported patches. 3. Reboot the system after kernel update.
🔧 Temporary Workarounds
Disable Bluetooth functionality
linuxDisable Bluetooth kernel modules to prevent exploitation
sudo modprobe -r btusb
sudo modprobe -r bluetooth
echo 'blacklist bluetooth' | sudo tee /etc/modprobe.d/disable-bluetooth.conf
Disable virtual HCI devices
linuxPrevent creation of virtual HCI devices
sudo rmmod hci_vhci
echo 'blacklist hci_vhci' | sudo tee /etc/modprobe.d/disable-vhci.conf
🧯 If You Can't Patch
- Disable Bluetooth functionality completely if not required
- Implement strict access controls to prevent unauthorized users from accessing Bluetooth devices
🔍 How to Verify
Check if Vulnerable:
Check kernel version and if Bluetooth modules are loaded: lsmod | grep -E 'bluetooth|hci_vhci'Check Version:
uname -rVerify Fix Applied:
Verify kernel version includes fix commits or check with: grep -r 'vhci_flush' /proc/kallsyms📡 Detection & Monitoring
Log Indicators:
- Kernel panic messages
- KASAN use-after-free reports in dmesg
- Bluetooth subsystem crashes
Network Indicators:
- Unusual Bluetooth connection attempts
- Multiple concurrent Bluetooth operations
SIEM Query:
source="kernel" AND ("KASAN" OR "use-after-free" OR "vhci_flush")